Optometer.



JOSEPH HARRY MARTIN, OF ROANOKE, VIRGINIA.

OPTOMETER.

Specification of Letters ltatent.

Patented Nov. 30, 1909.

Application filed July 18, 1907. Serial No. 384,407.

To all whom it may concern:

Be it known that I, JOSEPH HARRY MAR- TIN, a citizen of the UnitedStates, residing at Roanoke, in the county of Roanoke and State ofVirginia, have invented a new and useful Optometer, of which thefollowing'is a specification.

My present invention relates to improvements in instruments of the kindused by oculists and Opticians for testing the refractive qualities ofthe human eye with a view of determining what errors, if any, exist, andthe amount of correction necessary in each case in order that eyeglassesmay be fitted, and it has for its object to provide a combined testingand correcting instrument of this character that is not only capable ofreadily and accurately determining whether the eye is normal or whetherit is myopic or hypermetropic, either throughout the entire field or ona meridian or axis, as in the case of astigmatism, but it embodies anovel arrangement of lens sets that are capable of being readily set upin combinations to correct the refractive errors of the eye ineachparticular case, indicators being employed for directly designating thepowers of the spherical and cylindrical lenses employed in thecorrection, and also designating the axes of the latter.

Another object of the invention is to provide an instrument of thischaracter wherein plus or minus lenses of diflerent powers may beadjusted into the field of vision of the patients eye, either separatelyor in different combinations one with the other, the different lensesbeing placed before the patients eye or changed, as may be desired,without the necessity of uncovering the eye, accuracy in results beinginsured and the convenient arrangement of the lenses in sets ofdiiferent powers enabling the adjustments to be effected with thegreatest facility,

A further object of the invention is to provide an improved mode ofmounting a set of cylinder lenses, whereby the different lenses may bereadily brought into position and revolved until the axis of the lenscoincides with the axis of myopic or hypermetropic portion of the eyeunder test, the cylinder lenses being capable of the differentadjustments either separately or in combination with the plus and minusspherical lenses without disturbing any combinations that may be set upwith the latter, indicators being also supplied which designate thepower and the axis of the cylinder lens when the errors have beencorrected, it being thereby necessary to read the scales to obtain aprescription.

It is also an object of my invention to provide an improved sightingdevice in combination with the lens set described, whereby the patientseye may be readily prepared for testing, and a reading may be had thatwill indicate approximately the lenses necessary for correcting theerrors that exist.

To these and other ends, the invention comprises the various novelfeatures of construction and combination and arrangement of parts, whichwill be hereinafter more fully described, and pointed out particularlyin the appended claims.

In the accompanying drawings :-Figure 1 is an elevation of an opticalinstrument constructed in accordance with the present invention, theinstrument being viewed from that side at which the operator isstationed. Fig. 2 represents a detail view of the sighting device andits cooperating scales, the lens carriers being shown in side elevation.Fig. 3 is a detail view of the carrier for the cylinder lenses and otherdevices for determining the axis or meridian of the myopia orhypermet-ropia. Fig. 4 represents a section of the carrier for the pluslenses. Fig. 5 is a similar view of the carrier for the minus lenses.Fig. 6 is a sectional view of the carrier for the cylinder lenses andrelated devices.

Corresponding parts in the several figures are indicated throughout bysimilar characters of reference.

The instrument shown in the present embodiment of the invention embodiesa stand 1 of any suitable construction adapted to rest upon a table orother suitable support, it being provided, in the present instance, witha lamp or illuminating'device 2 whereby the object observed by thepatient during the test may have a fixed illumination.

A sight tube 3 is journaled in the stand on preferably a horizontalaxis, that end of the tube toward which the operator is stationed beingprovided with an adjusting wheel or disk 4, and the opposite end of thetube being provided with a disk 5 on which the carrier for the cylinderlenses is mounted. The carrier employed in the present instance iscomposed of a disk 6 pivotally attached to the disk 5 by means of apivot 7 and it is arranged to revolve about this pivot as well as aboutthe axis of the sight tube when the latter is rotated. The carrier 6 isprovided with a suitable number of apertures which are arranged in a rowconcentric with the pivot 7 and are adapted to register successivelywith the axis of the sight tube. Into these apertures are fitted a setof cylinder lenses 8 which are preferably graded progressively accordingto their refractlve powers, and the axes of all the cylinder lenses ofthe set are preferably arranged at right angles to the radii of the disk6 which pass through the centers of the respective apertures into whichthe lenses are fitted, any suitable mounting being employed forimmovably securing the lenses. These cylinder lenses are adapted toregister with the sight tube, and obviously by rotating the latter theaxis of each cylinder lens may be shifted into different angularrelations to the horizontal, and, in order to indicate the differentangular positions of these lenses, the adjusting disk at is providedwith a protractor scale 9 which cooperates with a pointer 10 secured toa relatively fixed part of the stand.

In order to assist the operator to determine the axis or meridian onwhich the error of refraction occurs, it is preferable to provide adiaphragm 11 in one of the apertures of the disk 6, the diaphragm beingopaque and provided with a very minute slit 12, the

slit being ordinarily about one inch long and one millimeter wide, andextending in a direction corresponding to the axes of the cylinderlenses, and this slit may be adjusted into different positions about theaxis of the sighting tube by rotating the disk 5, the purposes and modeof using the so-called stenopaic slit being well known in the opticalart.

In some cases, very accurate results may be obtained by cast-ing twoimages on the retina of the eye, the relative displacement of the imagesindicating whether there is an excess or deficiency in the refractivepower of the eye. This test may be applied, in the present instance, bythe aid of a pair of reversely arranged prisms 13 and 14: which arepreferably mounted in one of the apertures of the cylinder lens carrier,these p isms, in the present instance, being arranged base to base, andthe axes of the prisms preferably extending in a given directionrelatively to the axes of the cylinder lenses. As these prisms aremounted on the cylinder lens carrier, their axes may be shifted intodifferent angular positions relatively to the horizontal by rotation ofthe adjusting disk on the sight tube, the protractor scale and itscooperating indicator indicating the de gree of inclination of the axesof these prisms.

Secured to the stand is a septum 15 having an eye piece 16 through whichthe patient observes the test type or other object employed in the test,and on that side of the septum adjacent to the standard are mounted apair of lens carriers 17 and 18 for the plus and minus spherical lenses,the carrier 17 being pivoted on one side of the standard and having aconcentric row of apertures therein in which are mounted a set of plusspherical lenses which are preferably arranged progressively accordingto their powers and are adapted to register successively with the sighttube. The carrier 18 is mounted on the opposite side of the stand andprovided with a circular row of apertures in which are mounted a set ofminus spherical lenses 20, these lenses being preferably arrangedprogressively according to their refractive powers and being adapted toregister successively with the sight tube. Those portions of the threelens carriers which extend past the sight tube are arranged to overlapone another, the carriers being preferably composed of relatively thindisks fitted to operate very close to one another in order that thelenses of the three carriers may be setup in combinations with onlyslight spaces between them. In order to facilitate adjustment of thespherical lens carriers, it is preferable to cut away the opposite edgesof the septum, as at 21 and 22, in order to expose the peripheries ofthese carriers and thus faeilitate their adjustment. Extending from theopposite side of the standard from that on which the septum is arrangedare a pair of arms 23 and 24, the arms being preferably parallel andextending in a horizontal direction and parallel to the axis of thesight tube, and on these arms is mounted a slide 25 having a post orbracket 26 adapted to serve as a support for the test type or read ingmatter usually employed during the eye test, and these arms arepreferably of a length suflieient to permit the slide to be adjusted tothe various reading distances of different patients. One of the arms,the arm 23 in the present instance, is provided with a scale 27calibrated to designate the age of the patient, and the same arm is alsoprovided with a scale 28 to designate the acconnnodation of the eye, apointer 29 carried by the slide cooperating with both of these scales.The other arm, 21-, is provided with a scale 30 which is calibrated toindicate directly the refractive powers required to correct the errorsof refraction of the eye, a pointer 31 on the slide being arranged tocooperate with the lens scale.

In order to enable the operator to instantly determine the power of thelens or lenses before the patients eye, it is preferable to provide thedifferent lens carriers with suitable scales and pointers to co6peratetherewith, the cylinder lens carrier being provided with a scale 32marked according to the power of the lenses in the carrier, and thisscale cooperates with a pointer 33 secured to the periphery of the disk5 which revolves about the sight tube. The carrier 17 is provided with asimilar scale 34 which cooperates with a pointer 35 secured to arelatively fixed portion of the stand, such as to the septum, and thecarrier 18 is provided with a scale 36 which cooperates with a pointer37 which is also mounted on a relatively fixed portion of the stand.

In practice, the patient is stationed at the left hand side of theinstrument, as shown in Fig. 2, one eye at a time being applied to theeye piece, and the lens carriers are adjusted so that a vacant aperturein each disk registers with the sight tube, and this enables the patientto obtain an unaided observation of the test type or other objectarranged upon the slide. The oculist or optician may then adjust theslide longitudinally of the scale arms until the object appears theclearest to the patient. By reading the scale 30, the operator mayreadily determine approximately the power and class of spherical lensthat is to be used, a plus lens of the appropriate power being adjustedinto the line of vision by revolving the carrier 17 while a minus lensof the desired power is brought into the line of vision by appropriateturning of the scale 19, the pointers and 37 cooperating with therespective scales to enable the operator to correctly center the desiredlens in alinement with the axis of the sight tube. In many cases a lensto effect the required correction may be found upon either one of thesecarriers, but by simultaneously using the lenses of the two carriers, avery large number of combinations is possible, the different plus andminus lenses being set up simultaneously, and the resultant refractivepower being equal to the difference between the refractive powers of thetwo lenses employed In testing eyes that are astigmatic, the meridian oraxis of the astigmatism may be readily ascertained by the use of thesteno paic slit 12 which is brought into the line' of vision byrevolving the cylinder lens carrier, and it is rotated into difierentangular positions relatively to the horizontal by rotating the adjustingdisk 3, and when the meridian has been located, its angle may bedirectly determined by reading the protractor scale 9. Myopia orhypermet-ropia may be ascertained by the use of the double prism whichis also preferably mounted in the cylinder lens carrier, these prismsbeing brought into the line of vision by rotation of the carrier and therelative displacement of the images which are cast upon the retina ofthe eye will indicate whether the error of refraction is myopic orhypermetropic, the axes of the prisms being shifted into "differentangular positions relatively to the horizontal by manipulation of theadjusting disk.

After the meridian has been located and it has been determined whethertheastigmatic error is myopic or hypermetropic, the different cylinderlenses (minus or plus as the case may require) may be brought into theline of vision successively until a lens of the proper refractive poweris obtained, that is sufficient to correct the astigmatic error, thedisk 3 having been previously set so that the axes of the several lenseswill extend in the direction of the meridian of astigmatism of the eye.

By reading the scales of the lens carrier, a prescription is obtainedthat will enable the patient to obtain the proper lenses to correct theerrors of sight.

An optical instrument constructed in accordance with the presentinvention is not only capable of readily determining the errors ofrefraction of the eye, but it also embodies means for correcting theerrors, the correcting lenses being so mounted that they may bemanipulated with the greatest facility, and they are adapted for use incombinations that enable a large number of refractive powers to beobtained with a small number of lenses. Moreover, by arranging thedouble prism on the cylinder lens carrier, it is not only capable of usein those cases where spherical lenses alone would be sufficient tocorrect the errors, but it is also capable of determining whetherastigmatic errors are myopic or hypermetropic, so that the testing ofthe eyes may be accomplished quickly and accurately and with a minimumdiscomfort to the patient. Furthermore, the fogging effect to cause arelaxation of the muscles of the eye may be accomplished in either oftwo ways, that is to say, by adjusting the slide carrying the test typeuntil the latter is out of focus with the patients eyes, or a similarresult may be obtained by using a plus lens, the fogging being reducedby the minus lenses until the proper definition is secured, thedifference in the refractive powers of the two lenses corresponding tothe power of the lens to be prescribed.

lVhat is claimed is 1. An optometer comprising a suitable stand, a sighttube journaled in the stand, a graduated adjusting disk at one end ofthe tube, a disk eccentrically mounted on the other end of said sighttube and carrying optical testing means, said last named disk beingrotatable to carry the optical testing means into alinement with thesight tube and also having orbital movement about the axis of rotationof the tube, a fixed septum carried by the stand and provided with aneye piece in line with the sight tube, and lens carrying disks on theseptum on each side of the eye piece and each rotatable about an axiscarried by the septum to bring the lenses into the optical axis of thesight tube, and indices carried by the septum in operative relation tothe lens carrying disk thereon. Y

2. An optometer comprising a suitable stand, optical testing meanscarried thereby, parallel arms carried by the stem and projecting fromone side thereof, said arms having scale indications thereon, a slide onthe arms having a support for testing means, 1

and pointers on the slide, one pointer being arranged for one arm andthe other pointer for the other arm.

In testimony that I claim the foregoing as my own, I have hereto afiixedmy signature in the presence of two witnesses.

JOSEPH HARRY MARTIN.

Vitnesses J. H. DICKINSON,

C. E. Sownnn.

